Drop-out fuse construction



Jan. 11, 1949. w. o. SCHULTZ 2,458,742

DROP-OUT FUSE CONSTRUCTION Filed Nov. 15, 1945 3 Sheets-Sheet 1 INVENTOR. W/Zl/fl/M 0. Jaw/172' Jan. 11, 1949. w. o. SCHULTZ DROP-OUT FUSE CONSTRUCTION 3 Sheets-Sheet 2 Filed Nov. 13, 1945 W/lZ/AM 0. 50/1/02 ATTO/P/VEX Jan. 11, 1949. w, L Z 2,458,742

DROP-OUT FUSE CONSTRUCTION Filed Nov. 15, 1945 s Sheets-Sheet 5 I N V EN TOR. mum/17 0. Jc/Mrz BY I zzw W5 4 147 7 O/FWE X Patented Jan. 11, 1949 DROP-OUT FUSE CONSTRUCTION William 0. Schultz, South Milwaukee, Wis., assignor to Line Material Company, South Milwaukee, Wls., a corporation of Delaware Application November 13, 1945, Serial No. 628,157

6 Claims.

This invention relates to a drop-out fuse construction.

This invention is an improvement over that disclosed in my prior Patent No. 2,378,109 of June 12, 1945 for fuse construction and has the same general objects as those set forth in such patent.

Specifically, objects of this invention are to provide a drop-out fuse construction which is designed primarily for heavy duty and may be made as heavy as desired with the fuse tube as long as desired and with heavy contact pressure at both ends of the fuse tube assembly without unduly straining the fuse link and which insures complete extraction of the fuse link whether ruptured as a result of a large or small overload.

Further objects are to provide a construction which provides a positive latch between a movable active part of mechanism controlled by the fuse link and a part rigid with the fuse tube so as to relieve the fuse link of undue strain and also to prevent sagging or settling of the fuse tube assembly due to either a small degree of slackness in the fuse link or lost motion between the several parts of the mechanism.

Further objects are to provide a construction such that by far the larger part of the strain produced by suddenly slamming the fuse tube assembly into operative position is directly borne by the latch construction thus further protecting the fuse link from undue strain.

Further objects are to provide a drop-out fuse construction in which throw-out mechanism operates to throw out any remaining portion of the fuse link upon rupture on overload, before unlatching of the fuse tube assembly occurs to thus insure delay of the drop-out motion until the circuit is completely interrupted within the fuse tube.

An embodiment of the invention is shown in the accompanying drawings, in which:

Figure 1 is a view showing the device in operative position.

Figure 2 is :an enlarged view of the fuse tube assembly partly broken away and partly in section,

Figure 3 is a view looking upwardly from the bottom of the fuse tube assembly.

Figure 4 is a sectional view on the line 4-4 of Figure 2.

Referring to the drawings it will be seen that the device comprises a fuse tube I which is equipped with an upper contact structure 2 and a lower contact structure indicated generally at 3. The tube I may be formed of fiber or may be a composite tube formed of an outer sleeve 4 of Bakelite and an inner tube 5 of fiber. A fuse link is provided and extends through the tube. The tube it will be noted is open at both ends. This fuse link may comprise a fusible section 6 and a strain wire I, an upper terminal head or member 8, and a flexible leader 9. The tube is open both at its upper and lower ends as shown most clearly in Figure 2. The upper contact structure of the fuse tube may comprise a sleevelike member I which surrounds the upper end of the tube 1 and which is pinned or otherwise secured thereto, as shown in Figure 2. This upper contact of the fuse tube is provided with a manipulating eyeleted member H which may be engaged by a switch stick in the usual manner for rocking the fuse tube into operative position or pulling the fuse tube from operative position. The sleeve-like portion [0 of the upper contact is provided with an upper flange l2 which extends partway around and which is interrupted to allow the entrance of the upper edge of the pivoted clamping member l3 which is moved inwardly into clamping relation with the head 8 of the fuse link by means of a screw 14. It is to be noted that the head of the fuse link is preferably made with a downwardly directed substantially conical sleeve-like portion and that the flange l2 and the inner surface of the pivoted clamping member l3 are similarly shaped. It is preferable to provide a short stainless steel liner 16 which has a forced lit with the member as shown in Figure 2. This liner bears against the under side of the head 8 of the fuse link. The lower contact structure 3 of the fuse tube includes a rigid member ll which surrounds the lower portion of the fuse tube and is locked thereto. This member is split and is provided with a bolt l8 which clamps the member around the fuse tube, the bolt also serving to pin the rigid member IT to the fuse tube. The lower contact structure 3 is also provided with an overhanging partial tubular member i9 that is adapted to receive the end of a switch stick and an upwardly extending flange or web 20 to bear against the switch stick. It is provided with an eyeleted portion 2| to receive the pins of the switch stick in the usual manner so that the tube assembly may be lifted into or removed from the lower fixed terminal member hereinafter described. The rigid member I! which is fastened to the fuse tube is pivoted as indicated at 22 to a main lever 23. This main lever is provided with a pair of outwardly projecting trunnions 24 which fit within the hook-like portions 25 of the lower fixed terminal indicated generally at 26 in Figure 1. This main lever 23, therefore, is pivotally joined to a fixed portion of the fuse tube assembly as indicated at 22 and also pivotally joined by means of trunnions 24 with the stationary lower terminal 26. It is preferable to provide a stop screw 21, see Figure 2, on the main lever 23 to limit the relative angular motion of the main lever 23 with reference to the member H, the adjustable screw being arranged to contact with a portion of the member 1'! to thus limit its relative motion.

The main lever 23 carries at its free. end a pin or pivot member 28 which pivotally supports a throw-out lever or auxiliary lever 29 and a fuse link clamping lever 39. These levers are each independently freely revolubly mounted on the pin 28 carried by the outer end of the main lever 23. A spring 3| is interposed between the fuse link clamping lever or latch lever 30 and the throw-out lever 29. The throw-out lever 29 is provided with a pair of side flanges 32: between which the flexible leader or leaders 9: are positioned as shown in Figures 2, 3, and 4. In the form of the invention chosen for illustration, a double leader fuse link has been illustrated. These leaders are. arranged to pass around a curved portion 33 of the throw-out lever 29- and are adapted to be received between the clamping jaw 34 of the fuse link clamping lever 30 and a clamping portion 35 formed integrally with the main lever 23. The spring 3i thus acts tocause clamping of the leader between the members 34 and 35 and also biases the throw-out lever 29 towards throw-out motion.

It is to be noted particularly that the member H rigid with the fuse tube I is provided with a hook-like latch portion 36 which is engaged by a catch portion or foot 3'! formed integrally with the throw-out lever 29. This catch portion 35 is a relatively narrow member as may be seen from Figure 3 and passes freely into a slot 38 formed in the throw-out lever 29.

It is to be noted that the main lever 23 is prm vi'ded with rearwardly extending lips 39 which bear against a heavy contact spring 40 carried by the lower stationary terminal 26', see Figure 1.

It is to be noted also that the main lever is provided with a pair of feet or projections 4! which are adapted to strike portions 42 formed integrally with the lower terminal member 26 when the fuse tube has rocked to its lowest position and to thus serve to arrest further motion of the fuse tube assembly.

It is to 'be noted also that the lower terminal member 26 has a hood-like portion 43 which extends over the rear part of the lower fuse link controlled mechanism composed of the main lever 23 and associated parts. It is to be noted also that the member I! is provided with an outwardly extending flange 44 which extends outwardly on opposite sides over the outer or free end of'the lever 23 and over the throw-out lever 29. Thus the lower mechanism of the device is substantially protected by the overhanging members 43 and 44.

The upper stationary terminal is indicated by the reference character 45, see Figure 1, and both the upper and lower stationary terminals are carried by suitable insulators 45' which, in turn, are carried .by any suitable support, not shown, in accordance with the usual practice.

The upper stationary terminal member 45 carries a bail-like spring contact member consisting of a pair of arms 41 joined by abail portion 48 which is loosely held by means of an upwardly bent lip 49 formed on the upper terminal member 45. A pin 50 projects outwardly from the upper sta tionary terminal member d5 to limit the downward motion of the spring arm 47. These spring arms are provided with outer looped ends 5| and with inwardly extending upper arms 52 which are received beneath overhanging ledges or lugs 53 formed integrally with the upper terminal 45 so as to increase the downward resilient pressure of the lower arms 41.

' The lower arms 41 make contact with a pair of outwardly projecting pins 54 carried by the upper terminal 2 of the fuse tube. The lower arms 4! are provided with a downwardly bent portion 55. behind which the pins 54 are normally latched.

The construction hereinabove described is primarily intended for heavy duty service and a heavy contact pressure is obtained between the upper stationary terminal assembly and the upper terminal structure of the fuse tube and between the lower stationary terminal assemblyand the lower terminal structure of the fuse tube. Although heavy contact pressure is obtained, nevertheless, the fuse link is not unduly stressed. Instead it will be seen that the major part of the pressure is borne by the interlocking of the foot or shouldered portion 37 of the throw-out lever 29 and the catch portion 36 of the member I! rigidly fixed to the fuse tube. This interlocking is maintained until the throw-out lever 29 is released on rupture of the fuse tube on overload. This throw-out lever 29 quickly throws outany remaining portion of the fuse link even before any motion of the fuse tube assembly has oc curred. After the throw-out lever 29 has moved through a considerable angle, for example as shown in dotted lines in Figure 2, it is apparent that the shouldered portion 31 of the throwout lever is clear of the catch 35 which is rigid with the fuse tube and consequently the main lever 23 is free to rock downwardly thus moving the fuse tube downwardly and disengaging the pins or projections 54 of the upper contact 2 of the fuse tube from the hooked or latching portions 55 of the spring arms 47 of the upper stationary terminal and allowing the fuse tube to executedropout motion.

It is to be noted from reference to Figure 2' that continued motion of the throw-out lever 29 will cause the portion 56-, see Figure 2, of the throw-out lever 29 to engage an adjacent portion of the latching lever 38 and will thereafter cause the latching lever 30 and the throw-out lever 29 to rock as a unit about the pin 28 carried by the free end of the main lever 23. This releases the leaders of the fuse link and allows the throwout lever 29 to throw any remaining portion of the fuse link away from the fuse tube.

It is to be noted particularly that the throwout lever 29 operates very quickly and that after the throw-out lever has operated the fuse tube is free to detach itself from the upper terminal and to rock downwardly. This insures clearing of the circuit within the fuse tube prior tothe drop-out motion of the fuse tube. I

It is to be noted particularly that the interlocking between the throw-out lever and the catch, that is between the shoulder 31 of the throw-out lever and the catch 36, relieves the fuse link of the major part of the strain due to the weight of the fuse tube assembly and due to the heavy contact pressure.

It is also to be noted that excellent contact is obtained between the upper terminal of thefuse tube and the upper stationary terminal assembly and between the lower terminal of the fuse tube and the lower stationary terminal assembly.

It is to be noted also that the weight of the fuse tube assembly after release of the throwout lever and main lever by rupture of the fuse link is effective to cause rocking of the main lever 23. This rocking motion of the main lever 23 is augmented by the heavy contact spring 40 bearing against the lips 39. It is preferable to provide a thumb piece =57, see Figuresl and 3, on the throw-out lever 29 to facilitate manipulation of such lever during refusing. Also it is preferable to provide a latch member which is a U-shaped member 58 pivoted on the main lever 23 and adapted to be rocked over the free end of the latching lever 3% during refusing in accordance with my prior patent hereinabove noted. This temporarily latches the fuse link clamping or latching lever 30 and allows the easy threading or passing of the leaders 9 of the fuse link over the clamping lever 30 and under the clamping portions 35 of the member I! as discussed in greaterdetail in my above noted patent. After the throw-out lever has been moved into its 0perative position, as shown in Figures 1, 2, and 3, the temporary latching member 58 is rocked to the position shown in Figure 1 to release the latching lever or clamping lever 30 and to allow such lever 36 to clamp the leaders of the fuse link.

Obviously if a fuse link with a single leader is employed, this may be clamped as hereinabove directed with the same ease as with a two-leader fuse link.

It is to be noted from the description given immediately hereinabove that it is a simple matter to refuse the fuse tube assembly and that after such fuse tube assembly has been refused it may be lifted into position by a switch stick and its trunnions engaged within the hook portions 25 of the lower stationary terminal. Thereafter the switch stick is engaged in the eyelet H and the fuse tube assembly is rocked back into operative position.

Obviously as hereinabove described after blowing of the fuse link and drop-out motion of the fuse tube, such fuse tube assembly may be readily lifted from the lower terminal assembly by means of a switch stick and may be refused and replaced as described hereinabove.

On a relatively moderate overload the blast occurs from the lower end of the fuse tube. On very heavy overloads the upper button head of the fuse link is blown from the upper terminal of the fuse tube and the fuse tube vents from both ends.

In rocking the fuse tube assembly back into position after refusing the inward motion of the upper terminal of the fuse tube is limited by engagement of the web 59 of the upper terminal of the fuse tube with the adjacent portion of the upper stationary terminal 45. No matter how violently the fuse tube assembly is rocked back into operative position no excessive strain is imposed on the fuse link due to the interlocking of the throw-out lever and the catch as hereinabove described.

Also it is to be noted that the interlocking of the throw-out lever and the catch prevents sagging, although there may be some looseness in the fuse link and there may be some wear or looseness in the joints between the relative parts of the mechanism at the lower end of the fuse tube assembly.

It will be seen that a novel form of drop-out fuse tube construction has been provided by this invention which prevents undue stresses being imposed on the fuse link and which insures clearing of the circuit in the fuse tube when either a large or a small overload occurs as the throwout lever is effective under both conditions to assist in quickly withdrawing any remaining portion of the fuse link and also functioning to throw such remaining portion from the fuse tube assembly prior to drop-out motion of the fuse tube.

It is to be noted that the heavy contact pressure provided by the heavy downward thrust of the upper stationary terminal on the fuse tube results in a heavy downward thrust on the fuse tube itself. However, no harm results from this heavy downward thrust on the fuse tube as the major part of the strain incident thereto is borne by the interlocking of the throw-out lever and the rigid catch and is not transmitted to the fuse link.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. A drop-out fuse construction comprising upper and lower stationary terminals, a fuse tube having an upper end detachably locked to said upper stationary terminal, a main lever supporting said tube for drop-out motion and having pivotal connection with said fuse tube, a fuse link within said fuse tube electrically connecting said upper and lower stationary terminals, a catch rigid with said fuse tube, a throw-out lever pivoted to said main lever and normally having interlocking engagement with said catch and held against motion by said fuse link, said throw-out lever being biased towards throw-out motion and arranged to execute throw-out motion to withdraw any remaining portion of said fuse link from said fuse tube upon rupture of said fuse link and to detach itself from said catch, whereby said main lever will rock to allow said fuse tube to execute drop-out motion.

2. A drop-out fuse construction comprising upper and lower stationary terminals, a fuse tube having an upper terminal normally latched to said upper stationary terminal and detachable therefrom upon downward motion of said fuse tube, a main lever pivoted to said lower stationary terminal and to said fuse tube and biased towards rocking motion to lower said fuse tube, a catch rigid with said fuse tube, a throw-out lever pivoted to said main lever and having detachable interlocking engagement with said catch and biased towards releasing motion and normally restraining said main lever, and a fuse link within said fuse tube electrically connecting the upper and lower stationary terminals and passing around said throw-out lever and normally restraining said throw-out lever.

3. A drop -out fuse construction comprising upper and lower stationary terminals, a fuse tube having an upper terminal normally latched to said upper stationary terminal and detachable therefrom upon downward motion of said fuse tube, a main lever pivoted to said lower stationary terminal and to said fuse tube and biased towards rocking motion to lower said fuse tube, a catch rigid with said fuse tube, a throw-out lever pivoted to said main lever and having detachable interlocking engagement with said catch and biased towards releasing motion and normally restraining said main lever, a fuse link within said fuse tube electrically connecting the upper and lower stationary terminals and passing around said throw-out lever and normally restraining said throw-out lever, said catch bein of hooklike construction and said throw-out lever having a slot within which said catch is normally positioned, and having a shouldered portion normally resting on said catch.

4. A dropout. fuse construction comprising upper and lower stationary terminals, a fuse tube having an upper terminal normally latched to said upper stationary terminal and detachable therefrom upon downward motion of said fuse tube, a main lever pivoted to said lower stationary terminal and to said fuse tube and biased towards rocking motion to lower said fuse tube, a catch rigid with said fuse tube, a throw-out lever pivoted to said main lever and having detachable interlocking engagement with said catch and biased towards releasing motion and normally restraining said main lever, a fuse link within said fuse tube electrically connecting the upper and lower stationary terminals and passing around said throw-out lever and normally restraining said throw-out lever, releasable clamping means for clamping the lower end of said fuse link, said releasable clamping means including a stationary member and a clamping lever arranged to be moved to releasing position when said throw-out lever moves to throw-out position, and a spring between said throw-out lever and said clamping lever.

5. A drop-out fuse construction comprising upper and lower stationary terminals, a fuse tube having an upper terminal normall latched to said upper stationary terminal and detachable therefrom upon downward motion of said fuse tube, a main lever pivoted to said lower stationary terminal and to said fuse tube and biased towards rockin motion to lower said fuse tube, a catch rigid with said fuse tube, a throw-out lever pivoted to said main lever and having detachable interlocking engagement with said catch and biased towards releasing motion and normally restraining said main lover, a fuse link Within said fuse tube electrically connecting the upper and lower stationary terminals and passing around said throw-out lever and normally re-. straining said throw-out lever, and releasable clamping means for clamping the lower end of said fuse link, said clamping means being distinct and separate from said throw-out lever, said throw-out lever being arranged to release said clamping means upon throw-rout motion of said throw-out lever.

6. A drop-out fuse construction comprising upper and lower stationary terminals, a fuse tube having an upper terminal normally detachably latched to said upper stationary terminal, a rigid member secured to the lower end of the fuse tube and having a rigid catch, a main lever piv oted to said rigid member and to said lower contact and arranged to cause detachment of the upper contact of said fuse tube and the upper stationary contact on motion of said main lever, a throw-out lever pivoted to said main lever and having detachable interlocking engagement with said catch and biased towards releasing motion, a fuse link within said fuse tube electrically connecting said upper and lower stationary contacts and extending around said throw-out lever, said upper stationary terminal being arranged to provide heavy contact pressure against the upper terminal of said fuse tube and a heavy downward thrust on said fuse tube and the interlocking of said throw-out lever and said rigid catch coacting to relieve said fuse link of the major portion of the strain incident to the heavy downward thrust on said fuse tube.

WILLIAM O. SCHULTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,204,320 Schultz June 11, 1940 2,324,114 Schultz et al July 13, 1943 2,378,109 Schultz June 12, 1945 

